def main():
    n = int(input("how many days:"))
    #n can't smaller than 0
    while True:
        if n == 0:
            print("0 gold_coin")
            quit()
        elif n < 0:
            print('again')
            n = int(input("how many days:"))
        else:
            break
    coin_day = 0
    real_day = 1
    s = 0
    while True:#first day
        coin_day += 1
        # real_day += 1
        for i in range(0,coin_day):
            s += coin_day
            #check
            if real_day == n:
                print_ = str(s) + " gold coin"
                print(print_)
                return
            #second day
            real_day += 1

main()
